In the process of manufacturing semiconductor devices, there are steps in which a liquid source is vaporized to form a film over a substrate. In a vaporizing system that vaporizes a liquid source, one tank is charged with the liquid source so as to have the liquid source vaporized in this one tank. Then vaporized gas is taken out of the tank and sent to an external apparatus such as a film forming apparatus.
However, with conventional vaporizing systems, if the capacity of the tank is made smaller in order to make the vaporizing system smaller, a desired gas flow rate may not be able to be obtained. Further, if there is a limit on the specified store amount of the liquid source to be used, the number of vaporizing systems to be installed is restricted.